/* * drivers/base/dd.c - The core device/driver interactions. * * This file contains the (sometimes tricky) code that controls the * interactions between devices and drivers, which primarily includes * driver binding and unbinding. * * All of this code used to exist in drivers/base/bus.c, but was * relocated to here in the name of compartmentalization (since it wasn't * strictly code just for the 'struct bus_type'. * * Copyright (c) 2002-5 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * * This file is released under the GPLv2 */ #include <linux/device.h> #include <linux/module.h> #include "base.h" #include "power/power.h" #define to_drv(node) container_of(node, struct device_driver, kobj.entry) /** * device_bind_driver - bind a driver to one device. * @dev: device. * * Allow manual attachment of a driver to a device. * Caller must have already set @dev->driver. * * Note that this does not modify the bus reference count * nor take the bus's rwsem. Please verify those are accounted * for before calling this. (It is ok to call with no other effort * from a driver's probe() method.) * * This function must be called with @dev->sem held. */ void device_bind_driver(struct device * dev) { if (klist_node_attached(&dev->knode_driver)) return; pr_debug("bound device '%s' to driver '%s'\n", dev->bus_id, dev->driver->name); klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices); sysfs_create_link(&dev->driver->kobj, &dev->kobj, kobject_name(&dev->kobj)); sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver"); } /** * driver_probe_device - attempt to bind device & driver. * @drv: driver. * @dev: device. * * First, we call the bus's match function, if one present, which * should compare the device IDs the driver supports with the * device IDs of the device. Note we don't do this ourselves * because we don't know the format of the ID structures, nor what * is to be considered a match and what is not. * * * This function returns 1 if a match is found, an error if one * occurs (that is not -ENODEV or -ENXIO), and 0 otherwise. * * This function must be called with @dev->sem held. */ int driver_probe_device(struct device_driver * drv, struct device * dev) { int ret = 0; if (drv->bus->match && !drv->bus->match(dev, drv)) goto Done; pr_debug("%s: Matched Device %s with Driver %s\n", drv->bus->name, dev->bus_id, drv->name); dev->driver = drv; if (drv->probe) { ret = drv->probe(dev); if (ret) { dev->driver = NULL; goto ProbeFailed; } } device_bind_driver(dev); ret = 1; pr_debug("%s: Bound Device %s to Driver %s\n", drv->bus->name, dev->bus_id, drv->name); goto Done; ProbeFailed: if (ret == -ENODEV || ret == -ENXIO) { /* Driver matched, but didn't support device * or device not found. * Not an error; keep going. */ ret = 0; } else { /* driver matched but the probe failed */ printk(KERN_WARNING "%s: probe of %s failed with error %d\n", drv->name, dev->bus_id, ret); } Done: return ret; } static int __device_attach(struct device_driver * drv, void * data) { struct device * dev = data; return driver_probe_device(drv, dev); } /** * device_attach - try to attach device to a driver. * @dev: device. * * Walk the list of drivers that the bus has and call * driver_probe_device() for each pair. If a compatible * pair is found, break out and return. * * Returns 1 if the device was bound to a driver; * 0 if no matching device was found; error code otherwise. */ int device_attach(struct device * dev) { int ret = 0; down(&dev->sem); if (dev->driver) { device_bind_driver(dev); ret = 1; } else ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); up(&dev->sem); return ret; } static int __driver_attach(struct device * dev, void * data) { struct device_driver * drv = data; /* * Lock device and try to bind to it. We drop the error * here and always return 0, because we need to keep trying * to bind to devices and some drivers will return an error * simply if it didn't support the device. * * driver_probe_device() will spit a warning if there * is an error. */ down(&dev->sem); if (!dev->driver) driver_probe_device(drv, dev); up(&dev->sem); return 0; } /** * driver_attach - try to bind driver to devices. * @drv: driver. * * Walk the list of devices that the bus has on it and try to * match the driver with each one. If driver_probe_device() * returns 0 and the @dev->driver is set, we've found a * compatible pair. */ void driver_attach(struct device_driver * drv) { bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); } /** * device_release_driver - manually detach device from driver. * @dev: device. * * Manually detach device from driver. * * __device_release_driver() must be called with @dev->sem held. */ static void __device_release_driver(struct device * dev) { struct device_driver * drv; drv = dev->driver; if (drv) { get_driver(drv); sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); sysfs_remove_link(&dev->kobj, "driver"); klist_remove(&dev->knode_driver); if (drv->remove) drv->remove(dev); dev->driver = NULL; put_driver(drv); } } void device_release_driver(struct device * dev) { /* * If anyone calls device_release_driver() recursively from * within their ->remove callback for the same device, they * will deadlock right here. */ down(&dev->sem); __device_release_driver(dev); up(&dev->sem); } /** * driver_detach - detach driver from all devices it controls. * @drv: driver. */ void driver_detach(struct device_driver * drv) { struct device * dev; for (;;) { spin_lock_irq(&drv->klist_devices.k_lock); if (list_empty(&drv->klist_devices.k_list)) { spin_unlock_irq(&drv->klist_devices.k_lock); break; } dev = list_entry(drv->klist_devices.k_list.prev, struct device, knode_driver.n_node); get_device(dev); spin_unlock_irq(&drv->klist_devices.k_lock); down(&dev->sem); if (dev->driver == drv) __device_release_driver(dev); up(&dev->sem); put_device(dev); } } EXPORT_SYMBOL_GPL(device_bind_driver); EXPORT_SYMBOL_GPL(device_release_driver); EXPORT_SYMBOL_GPL(device_attach); EXPORT_SYMBOL_GPL(driver_attach);